This invention relates generally to reducing aerodynamic drag on vehicles such as trucks, trailors, etc. More particularly, it concerns the provision of means to eliminate or reduce the drag inducing effect of airflow through the gap between vehicle components, as for example between truck tractor and trailer units.
It is found that a major cause of aerodynamic drag in tractor-trailer or tractor semi-trailer combinations, is the gap between the tractor and trailer units. Certain of the relative airflow over the tractor cab passes downwardly into the gap and then outwardly at the gap bottom and lateral sides, disturbing the airflow along the vehicle and creating drag. Lateral cross-winds or gusts entering the gap have the same drag inducing effect. While certain so-called air deflectors have been provided on tractor cabs in the past, they do not operate in the manner provided by the present invention to reduce drag induced by airflow through the gap, and they tend to produce airflow conditions which do not sufficiently resist cross-wind flow into the gap.